4.6 P38 not running well - help

in the last week my 4.6 p38 has not been running very well, i refilled with fuel in case the petrol had been the problem but its still the same.

the engine is hesitating when accelerating but its ok at pulling away, its like its missing or starved of fuel, there is a bit of vibration from the engine at certain revs but not all the time, also when i put cruise control on it gets slower and slower and becomes a waste of time using it.

since it started doing this it has not got any worse or better, does anyone have any ideas what it could be or suggest thing i could check, please dont let it be expensive to fix

When you say it's hesitating on acceleration, is that when you initially press the accelerator? If so, does it do the same when you rev it in neutral?

If so, it could be the MAF... Mine was doing that and a new MAF cured it completely.

Just my non-expert theory...

kooky_guy said:

When you say it's hesitating on acceleration, is that when you initially press the accelerator? If so, does it do the same when you rev it in neutral?

If so, it could be the MAF... Mine was doing that and a new MAF cured it completely.

Just my non-expert theory...

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it does not do it when initially pressing the accelerator but it does do it higher up the rev range, more noticable in 3rd gear (auto)

i had an audi tt with a faulty maf, to make sure it was the maf you had to disconnect it and it went a lot better with it unplugged then it was the maf, does this kind of test work on the rangie

mystic.bertie said:

it does not do it when initially pressing the accelerator but it does do it higher up the rev range, more noticable in 3rd gear (auto)

i had an audi tt with a faulty maf, to make sure it was the maf you had to disconnect it and it went a lot better with it unplugged then it was the maf, does this kind of test work on the rangie

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Apparently so, but the engine should be warm first.

Doesn't sound like the MAF from what you've said, but it's easy enough to try the test.

Try changing your plug leads, they often detiorate over time and only malfunction under load i.e. when accelerating. I would change these first as they are only £25 ish on P38spares.co.uk

kooky_guy said:

Apparently so, but the engine should be warm first.

Doesn't sound like the MAF from what you've said, but it's easy enough to try the test.

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i did not notice any improvement with the maf plug off, i timed myself to 70mph and 15.6 with the maf on and 16.5 with the maf off.

with the maf on i got 11.6 secs to 60mph and i think it should be 9.6 secs

Nidjet said:

Try changing your plug leads, they often detiorate over time and only malfunction under load i.e. when accelerating. I would change these first as they are only £25 ish on P38spares.co.uk

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im reluctant to just go buying things in the hope i find the fault, my next move was going to be checking and removing the spark plugs ill see how the leads look, this problem just appeared all of a sudden, not like a gradual deterioration.

i had the plugs off and cleaned them, a couple were rusty on the nib so i cleaned them all up, the leads looks like they could do with being replaced also and the air filter.

whats puzzling me is why is the cruise control not working properly either, if i set it when driving at 60mph it just gets slower and slower and slower

mystic.bertie said:

i had the plugs off and cleaned them, a couple were rusty on the nib so i cleaned them all up, the leads looks like they could do with being replaced also and the air filter.

whats puzzling me is why is the cruise control not working properly either, if i set it when driving at 60mph it just gets slower and slower and slower

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Sounds like you could do with new HT leads in any case then.

It might not be related. The Cruise Control problem sounds like it might be a vaccum leak. Check the pipes on the jobbie on the end of the EAS box - they may be starting to split.

Guy

kooky_guy said:

Sounds like you could do with new HT leads in any case then.

It might not be related. The Cruise Control problem sounds like it might be a vaccum leak. Check the pipes on the jobbie on the end of the EAS box - they may be starting to split.

Guy

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i had searched and read about the split vacuum hoses, i checked mine and bingo they were split, i had hose in my garage the right size so i replaced it and not my cruise is working great again.

i have adjust the throttle cables as these were very slack, the throttle and cruise cable, so ill see how it feels to drive but it may be worth replacing all the sparkplugs and leads and filters and oil etc.

the previous owner 'sirus' claimed he had done the servicing but it looks like a few pork pies were told when i bought this rangie. i must say i expected better.

when changing plugs,i have been told that leads should be changed at same time.ihave found this out to my costsee my recent threadbest of luck with her p38 4.0 cat problem?

stevek7741 said:

when changing plugs,i have been told that leads should be changed at same time.ihave found this out to my costsee my recent threadbest of luck with her p38 4.0 cat problem?

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hi i read your thread, i have never had to replace leads unless they were actually faulty, i think the dealers are telling porkies if they say they should be changed with sparkplugs, if the leads are sound why replace them, i hope you get your problem fixed matey

i have just been a run, my cruise is working just fine and the car is driving a lot better after cleaning up the plugs, i still feel it is down on power slightly you feel it more so at kickdown, ill give it a service and see how it feels after all that has been done.

mystic.bertie said:

the previous owner 'sirus' claimed he had done the servicing but it looks like a few pork pies were told when i bought this rangie. i must say i expected better.

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Seems to be par for the course with P38s!
Mine was described as being perfect with everything working. Like hell!

Guy

kooky_guy said:

Seems to be par for the course with P38s!
Mine was described as being perfect with everything working. Like hell!

Guy

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everything working , except the heated seats, except the sat nav speaker, except the air con, except the passenger window sticking, except the non existent jack and wheel spanner. Honesty just dont exist these days, thats a forum mod for you eh, tell you any písh and have me travel 350 miles, worse still i actually asked if everything worked ok, i never tested everything as i actually thought the guy would not lie to me and i did kind of trust him because he was a forum mod, looks like there just as dishonest as the next bloke when selling cars.

seems to be something to do with old style leads were made from 100% copper wire and now modern leads only have copper heads and are more prone to need replacing on a more ragular basis.hoping you are only having a minor irritant,the good times make up for the bad

replaced the air filter, oil filter, oil, sparkplugs, ign leads.

apparently there is no fuel filter

now the rangie is going much better now, feels like it should do.

the main problem with it not running well was the ign leads

the problem with the cruise not working was the leaking vacuum hose.

happy days again

glad too see you got her going again happy days:clap2::clap2:best of luck to you for the future and many happy miles:5bparty: